Art of photogravure color printing



Feb. 22 1927.

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ART OF PHOTOGRAVURE COLOR PRINTING Filed Jan. I5, 1922 l.6 `Sl'xeetls-Sl'xeei'. 4

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UNITED STATES' PATENT OFFICE.

-BENJAMIN FRANKLIN rrrrromsou,A or' Los ANGELES, CALIFORNIA.

ABT OF PHOTOGRAVURE COLOR PRINTING.

Application led January 3, 1922. Serial No. 526,523.

The carrying out plementafifyjiprinting plates, which, when printed* in connection with photographic half-tone printing plates in suitable colors of ink, will produce color prints similar in photo engravers as duotones; or, if two supple- `mentary plates be used with properv inks, the

result 1s a print similar in appearance to thoseknown to photo engravers. as tricolor prints; and with three supplementary plates, used with the proper inks, a print similar to those known to photo engravers as quadricolor is produced. The results are not identical, but they are similar.

The supplementary plates produced by my improvement in this art may also be printed as supplementary color plates to line-etched plates; either one or more supplementary lates being used with suitable colors-of ink), producing a result differing from anything now" used by photo engravers, but somewhat similar in appearance to the result attained by what is known to photo engarevers as the Ben Day process, although this newly discovered method of production is Ventirely different from, and more economic of operation, `than any process heretofore known.

Objects and advantages of this improvement are: l Y

To .produce color printing plates and multicolor prints at less expense than heretofore.

To produce photographic half 'tone sup-y plementary color plates to print in connection with photographicV half-tone plates made at a previous time.

An object of this invention is to enable the ownerof an ordinary photographic halftone plate, which he has already purchased and probably used inthe production of onecolor'printing, to utilize such plate for the production of multicolor prints.

Another feature of the invention is the predeterm-ining of the characters, the

amounts, and the locations of colors that are required to produce the desired effect in of this invention involves anew process for producing sup the combined impressions of the several plates.

Other objects, advantages and features of invention may appear from the accompanying drawings, the subj oined4 detailed description and the appended claims.

An object of this invention is to so prepare camera copy for photographic halftone supplementary color plates, that v-in making the negative therefrom a prism attachment may be used upon the camera, and

may be photographed the camera cop?I oid upon which it has been through the cellu prepared, thereby gaining the advantages of photographing the camera copy through a prism, -and of photographing it through Celluloid Yand also of avoiding the necessity of the photo engraver stripping the negative from the glass plate, upon which it ywas photographed, and transferring it in reversed position to/another glass plate prior to printing theY image upon the printing plate to be etched. Where the lines of twoV or more plates must registenone upon another, it 1s necessary to avoid transferring the negative, which has a tendency to lose its shape during the transfer.

An object of this invention is to avoid the danger or likelihood of any distortion ofV the negative either from camera vibration or negative displacement during the operations of preparing the negative for printing upon metal,` Y

It is ldesirable in producing negatives from camera copy for the production of photographic half-tone supplementary color plates, that a camera of fixed focus be used to insure vcorrect register of the supplementary plate with the key plate; and it is also desirable to print the negative through the use of a prism attachment so that the camera copy canbe more rigidly placed in a square position vwitlrrelation to the photographic plate, thereby pre-venting distortion of the negative. Y f

In the production of a photographic halftone supplementary color printing plate, I produce through a prism, a camera copy negative in correct position on its plate, Yfor immediately printing upon the metal, without stripping, removing, reversing or displacing the negative from its plate.

In carrying out this invention, the camera copy for the'production of the photographic half-tone supplementary color printing plate is prepared upon a sheet `of thin mat Celluloid in such a manner that by reversing the sheet and photographing the camera copy through the Celluloid, While using a prism attachment to the camera, a nevative is produced in the correct position toibe printed upon the metal, thus avoiding any likelihood of distortion or relative displacement of parts ot' such negative.

An object is to secure a greater smoothness of surface in the camera copy; that is to say, an absence of any appearance of brush marks in the finished plate.

Another object is to facilitate properly placing high lights, shadings and details in the correct position for registry with the key plate when such high lights shading or de tails, appear in connection with colors in the supplementary plate.

In this broadly new and pioneer method, I provide and use one or more tone determiner proof sheets and preferably a sheet which is a photo-engraved multi le shade sheet and may have the various siades arranged in regular or irregular forms, as spots, blotches or stripes. A regular arrangement of regular stripes is preferred, and will be illustrated herein,

The accompanying drawings will assist in the understanding of the new discovery and invention.

Figure 1 represents a specimen of the pre ferred type of tone determiner; a sheet of multiple-shade proof-paper printed from a photo-engraved printing plate and adapted for use in one of the steps involved in my improvement in this art. Orange is the color shown in this instance.

Fig. 2 represents fragments of similar tone determiner or proof sheets, of different colors; viz, blue, purple, and yellow.

Fig. 3 represents av key or tint-guide sheet for use in this improved art; the same, in this illustration, comprising two sets of stripes; the stripes of one set being in angu lar relation to the stripes of the other set; the stripes of each set varying in intensity, as from black to very light grey in'one set, and from solid oranve to a light orange tint in the other, showing numerous combinations of two colors.

Fig. 4. is a view of a like key or tintfuide sheet, showing another' combination oia tivo colors in numerous tints.

Fig. 5 is a fragmental view of a key or tintguide sheet of another combination of two colors.

Fig. 6 is a fragmental view of a Celluloid mat tone determiner came-racopy for use in, or toward, the production of what is shown in Figs. 1, 2, 3, 4, 5, 7, S and 10.

Fig. 7 is a fragmental View of a multipleshade print from a half-tone proof-paper printing plate made from the Celluloid mat shown in Fig. 6.

Fig. S is a fragmental View of a multipleshade print from the saine proo'fepaper print 1f ing plate, as Fig. 7, printed with another color.

Fig. 9 is a guide print made by offsetting on a thin sheet of celluloid, an ink impression from the key plate and is' to be used in mak ing camera'copy for the half-tone supplenientary printing plate.

Fig. 9 is a fragment of a photo-engraved key plate.

Fig. 5) is an ink proof from the key plate.

Fig. 10 is a view of the tone determiner proof, being in this instance a striped multiple-shade sheet ot red proofpaper with the nnpression thereon ot' the photo-engraved printing plate from an impression of which Fig. 9 is an otl'set.

Fig. 11 is a View of the workmans shade kit containing one white, one solid black, and several shades of grey, oil or water color, and the color characters appropriate thereto.

Fig. 12 is a fragmental View ot a celluloid camera-copy made from the guide print shown in Fig. 9.

Fig. 13 is a print from a half-tone printing plate produced by painting the reverse side of the Celluloid guide print sheet shown in Fig. 9, and then erasing the guide print from said sheet, in the usual manner; the negative for its production being ma'de by the reverse side of the Celluloid camera copy shown in Fig. 12.

Fig. 14 is a view of the finished product which is a print com )rising an impression in one color, of a photographic half-tone printing plate, or a line-etehed printing plate, forming a picture; and an impression in another color, of a photographic halttone printing plate of portions of said pictture in varying shades; and may be with or without additions to said picture.

Fig. 15 is a view of a set of live sheets of red tone determiner proof paper by the use. of which it is possible to predetermine the shades or tints for a supplementary plate adapted for printing the supplementary impression shown in Fig. 14.

The method used in producing supplementary color printing plates by this process is as follows:

First: The working colors areprepared. They may be of any photographically suitable character and are preferably black and several shades of grey. The colors and shades or tints are designated throughout the paraphernalia or devices employed by the Workman, by corresponding colorl char acters o, for the applied paints and a for the unapplied paints, and which are shown as Arabic numerals; the numeral l being used for` the solid color and successive numerals as 2, 3, el, and 5 being used for the successively lighter shades or tinta thereof. It is necessary that unifornlity ot thus arranging the colors, shades oltints be followed in the case of learners or ordinary Vworkmen and it is essential to this process that the exact formula of color and shades or tints thereof adopted for the use of the workmen shall be maintained throughout the process.

Preliminary to beginning the production of the supplementary printing plate, the w rkman will be supplied with the requisite rking colors or paints b which, for conenience andfto avoid mistakes arerdesignated on the color tray t with the numerals indicated by the color characters a.

A stock of proofpaper sheets for the purpose of predetermining the proper tints or intensities of color desirable in the various parts of the supplementary color printing plate or tint plate to be produced, is printed with inks of the various colors usually used as the supplementary colors for the finished prints, and is kept on hand, ready for use as required. Each 'sheet of such proof paper is printed in one color which usually comprises sections of different shades or tints and is called the tone determiner. Specimens of various tone determiner proof sheets are shown fresh in Figs. 1 and 2, and such sheets are marked with the character c wherever any specimen is shown in the drawings. See Figs. 1, 2 and 10.

, This multi-tint tone determiner c is prepared as follows: A sheet d of thin mat celluloid having a smooth side ispainted on the mat side with the entire'succession of working colors or paints b (see Fig. 11) decided on for use throughout the process.

any color and shades and tints thereof These paints are preferably photographically suitablewater colors and they are applied in sections, most desirably in bands or stripes b', of black and greys in successively lighter shades. See Fig. 6.

The sections of xlike color or tints are respectively marked throughout with-the appropriate designating character l, 2, 3,, 4, or 5 as indicated'by a in said Figs. 1, 2 and 10 and other views.

This sheet of celluloid d is reversed and a photographic negative of the reversed sheet photographed through the celluloid, is produced, and its image is fiat etched upon copper or zinc. in the manner usual to photographic 'half-tone processes, thus producing a photoengraving showing varying intensities of shade, the ink impressions from which constitute the multiple-shadel print c', Figs. 7 and 8, and will of course, exhibit -the same relative intensity of shades irrespective of the color"in which the impression is printed. With such copper or zinc cut, not shown, I print the tone-determiner paper sheets c.

In producing the tone determiner proof paper sheets c, black andl shades of grey have been indicated for camera` copy; but may should be preserved as record, and the same formula always be used by the workman in preparing camera copy for supplementary plates, as hereinafter described.

Second: Tint guide sheets,e, as in Figs. 3, f1, 5, are prepared for the purpose of observing the Vcolor phenomena which results from the printing of different colored inks on a common surface as governed and modified by the density of half-tone dots. This tint uide sheet is used by the workman as an auxi iary to the tone determiner proof sheet c, in preparing camera'copy for supplementary plates. Itis also used by the artist in preparing the copy for key plates p, and by any person directing the work of such artist and workman to determine the possibilities-of color and shades of any two inks printed upon a common surface.

This tint guide sheet, e, is prepared as follows: A photoengraved cut is made as described for the production of tone determiner sheets in bands of color and shades thereof or other -convenient arrangement, the angle of the dot in imposing the photographic half-tone screen, being` 45 degrees.- A second photoengraved cutl of the'same copy is then made, the angle of the dot being 30 degrees. An ink impression from the rst cut is printed with the striped sec- 'tions or bands l, 2, 3, and 4 running horizontally with the paper. An ink impression from the second cut is. printed upon the common surface, with the lines running perpendicularly; the first engraving represents the tint in solids, middle tones and highlights, and the second engraving represents the key in solids, middle tones and'highlights. These tint guide paper sheets, or key sheets, are prepared in the two colors of ink which it is desired to use in combination and in as many varieties of combinations of such two colors and their tints and shades as is required.

Third: A proof f of the photo-engraving or line-etched plate for which it is desired to produce a supplementary tint plate or plates and which is hereinafter referred to as the key plate, shown at 79 in Fig 9a, is made upon a sheet c of the tone'determiner paper previously prepared in the exact color in which it is intended the supplementary tint plate is to be produced. The impression f ofthe key plate is printed upon the tone determiner proof sheet c, Fig. 10, in the eX- act color in which it is intended to be print- `thenmade in strong red ink frointhe key plate, andan offset impression h thereof (see Fi 9) is made on the smoothside n of a s eet d of thin mat Celluloid. This Celluloid sheet d is then reversed as shown in Fi 9 and the workman supplied with the b ack and y paints b exactly alike in formula to tie paint used in producing the camera copy from which the engraver produced the photoengraving, plate p, used 1n making the tone determiner proof paper c shown in Figs. 1 2 and 10 and making the guide sheet e, Figs. 3, 4 and 5, and tone determiner paper lc, Fig. 15.

The sheet d' of Celluloid shown in Fig. 12 is used by the photoengraver as Camera copy from which to make the negative used in producing the supplementary plate photoen raving.

gfhe key plate impression g is preferably printed in red in order to enable the Work- `man to most readily distinguish the details ,i of the guide print h on the smooth underside n of the Celluloid sheet d', through the Celluloid-While painting the camera copy on the mat side of the Celluloid with black and shades of ley. If any other Color than strong red e used for the guide rint, the lines thereof will not be so easi y distinguished while painting with black and grey on thc mat side m.

It is essential to this process that the workman shall always use colors of the same formula (and therefore the same shades) as were used in making the photo engravings from which the tone determiner proof papers c, lc and tint guide sheets e were produced.

Thesvorkman then proceeds to paint camera copy z', (Fig. 12), on the reverse side of the Celluloid sheet d through which he can sce the red offset print h, of the key plate, which serves as the Workmans guide as to where to paint. lVhile doing this the workman has before him the tint guide sheet e, Fig. @l and the tone determiner proof, as in Fig. l0, which furnish him with a inechanically accurate guide as to the shade of grey or black with which to paint, to secure the proper intensity of shade in the supplementary plate. and to produce the desredcolor `and tint in the finished Color print. The tone determiner proof f, Fig. 10, of the Fig. 14, and is printed upon tone determiner Y paper of the color and shades thereof to be used in rinting the supplementary plate in the finis ied print.

The success of this rocess depends on the workman painting tie proper shades of black and grey on the Camera co y i, Fi 12; and to erable him to do thisll provi e a guide'proof combining the color and the densities thereof in.` the key late impression f with the color and the ensities thereof which it is proposed `to use in printing in the finished print, the supplementary color, shown, for instance pinkor red, as indicated at j in Figs. 4, 10, 14 and 15.

An advantage of using multiple tint tone determiner proof paper c is that it makes it easy for the workman to compare various ores, i. e., solids, middle tones and high ior its.

bFor great exactness, the workman will be provided with one proof of the key plate printed on tone determiner proof paper c having the bands of color as in Fig. 10; and will also be provided with other roofs of the key plate, each printed on a ull sheet, thus forming a set of tone determiner proof paper sheets each composed of one single tint or shade, as in Flg. 15. In painting camera copy for the tone determiner tint guide sheet and for painting Camera copy for supplementary plates, lI use a sufficient number of such solids, tints and shades as are most practical for ordinary commercial purposes, i. e., four, more or less as may be desired.

Fifth. The offset print Ii. of the key plate used has a guide print by the Workman in painting, the camera copy is now erased from the Celluloid d by sponging with benzine; and then a photographic half-tone negative, notV shown, is made of exactly the same size as the camera copy It is advisable to use for this purpose a fixed focus camera equipped with a prism.

The camera operator will ascertain the angle of the. dots of the screen in the key plate an place the camera copy z' upon the camera Copy board (not'shown) in such position that the angle of the half-tone dot `in the negative of the supplementary plate will vary thirt degrees from the angle of the half-tone ot in the key late, in order that the half-tone dots in tie key plate and supplementary plate may properly register.

In making this negative the camera copy is photographed with the mat side m of the Celluloid on which the camera copy z' is painted, away from the lens, thus photographing through the Celluloid; the smooth side n of the Celluloid sheet d from which the guide print h hasl been erased,. being lori also in reverse; but when the celluloid is reversed in its exposure to the camera the position of the camera copy is corrected for photographing through the prism attachthe metal plate.

ment which will thus impose the negative in the proper position to be printed upon After the negative made from the camera copy z' is printed upon the copper or yzinc plate, it is yetched in the usual manner, producing the supplementary printing plate with which the supplementary print o, Fig. 13, may be printed. By printin with the key plate and the vsupplementary plate in the usual way and wlth the selected inks,

the final two-color print g, Fig. 14, is pro duced.

I claini.

1..The method set kforth of 1producing a 'half-tone printing platev whic painting the camera copy for a sup 1emen' comprises tary' v print, with colors corres n ing in actmic valuei to the shades of co or required in the finished print, and thus predetermining the tones to be produced from said halftone printing late. y I

2. The met od set forth of preparing camera copy for a supplementary plate to be used in `conjunction with` a key plate for producing superposed impressions to form a n .to tmts,. tones or shades requlred 1n the de- Siredrmt.

rint, which method consists in printing'an impression of the key plate making an olfset of said im ression upon a thin, trans- S'sheet of celluloid, using said key ression as a guide viewed throng the celuloid, for determining the places where the paint is to be applied, and whereby thel parent celluloi copy upon the other side of sai transparent late 1mlcamera copy is adapted to be photographed through a prism in producing the negative 4lfor the supplemental print.

lv3. The method set 'camera copy for a supplementary p ate to be used in conjunction with a key plate for producing lsuperposed impressions to form a pri-nt, which method consists inl painting the camera copy upon the mat side of a4 sheet, paintin the cameral .one color #in varlous shades and paint camera co y for a supplementary plate forth of pre aririgv transparent sheet of mat cellulod, having a smooth side upon which is` an impression of the key plate so that the key plate impression may serve as a guide viewed through the celluloid, for determinin the places where the paint is to be app ied, and the camera copy is adapted to be photographed through a prism in producing` the negative for the supplemental print.

4. The method set forth of pre aring camera copy byv asupplementary pllzite tc be used in conjunction with a key plate for producing superposed impressions to form a print, which consists in4 painting the cam-l era copfy vu on one side of a ltransparent sheet o ce luloid upon the other side of which is an'impression of a keyplate so that thekey plate implression may serve as a guide throughthe ce uloid for determining the places where the paint is to 'be ap lied; and predetermining the tones and shades by usin aints of various shades indicated by a gul e rint made up of dots uniform to each sha e.

5. In the art of producing polytone prints,

the fnethod .of predeterminlng the tones of asupplementary printing plate which consists in painting the camera copy therefor with paints of 'various shades and predetermining the shades or tints or tones ofthe finished print b a tone determining uide sheet having a key plate impression giereon, and a tint guide sheet containing sections of tints, tones or shades corresponding '6. -he art of producing polytone prints set forth which consists in usin paints of ensities to tially as set fort In testimony whereof, I have hereunto set v my hand at Los' Angeles, California, this 24thday of December, 1921, y

BENJAMIN FRANKLIN HUTCHISON. 

